<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Title</title>
    <style>
        .master{
            width: 400px;
            margin: 100px auto;
        }

        .master .top{
            height: 50px;
            font: 16px/50px 宋体;
            padding-left: 20px;
            width: 380px;
            background-color: #0099cc;
            color: white;
        }

        .master .body{
            height: 2px;
            background-color: green;
            transition: all 1s ease-in-out;
        }

        .top:hover+.body{
            height: 100px;
            background-color: pink;
        }
    </style>
</head>
<body>
    <div class="master">
        <div class="top">今日新闻</div>
        <div class="body"></div>
        <div>
            <div class="top">今日新闻</div>
            <div class="body"></div>
        </div>
        <div>
            <div class="top">今日新闻</div>
            <div class="body"></div>
        </div>
        <div>
            <div class="top">今日新闻</div>
            <div class="body"></div>
        </div>
    </div>

</body>
</html>